Concrete anchorages



April v19-57 A. H. FILLING 2,788,652

CONCRETE ANCHORAGES Filed Feb. 7, 1952 Q N g g llmmll INVENTVOR.

United States Patent CONCRETE ANCHORAGES Alan H. Pilling, New York, N.Y., assignor to Richmond Screw Anchor Company, Inc., New York, N. Y., acorporation of New York Application February 7, 1952, Serial No. 270,459

2 Claims. (Cl. 72-405) This invention relates to concrete anchorages,and more particularly to those of the type which, when placed in theconcrete mass, will provide means for threadable engagement with a boltor other screw-threaded element. In various types of concreteconstruction, it is often desirable to provide bolt-receiving means bywhich form parts can be maintained for progressive concrete pouring. Itis desirable that such bolt-receiving means shall be [firmly embedded inthe concrete mass without being of such size therein as to occupy anobjectionable amount of space and thus weaken the mass. This isparticularly true of low quality concrete, or that in which the mixcontains a relatively small proportion of cement.

It is therefore an object of the present invention to provide a concreteanchorage which will be particularly useful for placement in low qualityconcrete; which will afford a firm anchorage for a bolt or otherthreaded element and which will provide a maximum of resistance todisplacement under strain or stress.

With these and other objects to be hereinafter set forth, in view, Ihave devised the particular arrangement of parts to be more fullydescribed and set forth in the claims appended hereto.

In the accompanying drawing, wherein an illustrative embodiment of theinvention is disclosed:

Fig. 1 is a top plan view of a concrete anchorage constructed inaccordance with the invention;

Fig. 2 is a side elevation of the anchorage, showing the provision of anangular portion at one end thereof; and

Fig. 3 is a sectional view, taken on the line 3--3 of Fig. 1, looking inthe direction of the arrows.

Referring to the drawing and to the embodiment therein shown, 1 and 2indicate a pair of parallel metallic rods of suitable length, accordingto the body of concrete which is to surround them. Adjacent to one endof the parallel rods 1 and 2 is a spiral helix "3 which constitutes thebolt-receiving end of the anchorage. The spiral helix 3 is preferably,but not necessarily, formed of flat strip stock coiled into helicalformation, with its convolutions properly spaced to engage the threadson the bolt or other threaded element that is threadably inserted withinthe helix. At its periphery the helix 3 has its convolutions secured tothe two spaced rods 1 and 2 as by being securely welded thereto, suchattachment of the helix to the rods acting to maintain the convolutionsof the helix in the proper spaced relation to thread ably receive thebolt.

Adjacent to the opposite end of the rods, and positioned between thesame is a second helix, indicated at 4 which is employed for the solepurpose of materially aiding in the anchorage of the device in theconcrete.

2,788,652 Patented Apr. 16, 1957 That is to say, the convolutions 5 ofthe helix 4 are spaced rather widely apart to permit of a maximum ofconcrete to enter between the convolutions and thus strongly resistaxial or other displacement of the anchorage out of the concrete. Theconvolutions '5 of the helix 4 are preferably of greater pitch thanthose in the helix 3 and are not employed for engagement with the boltor other threaded element that is inserted in the bolt-receiving helix3.

The two helices 3 and 4 are shown as being of the same outside diametersto maintain uniform spacing between the rods 1 and 2. The insidediameters of the helices need not be the same.

In the form shown, the two helices 3 and 4 are shown as separated orspaced apart with an intervening space 8 between them. If desired, asingle continuous helix might be employed, or one which extendscontinuously from one end of the rods to the other end and withoutinterruption and having the pitch of the convolutions at one end greaterthan at the other end.

The two rods 1 and 2 between which the two helices are secured, can beperfectly straight, as seen in Fig. 1, or the same might be bent as at 6to thereby provide an angular end portion 7, which latter portion 7 willreceive the helix 4. In such an arrangement, any force exerted on theanchorage on a straight line along the axis of the helix 3 will bestrongly resisted by the angular position of the opposite end of theanchorage.

To aid materially in providing resistance to displacement of theanchorage, it is preferable that the helix 4 shall be made of flat stripstock, thus providing relatively wide and fiat surfaces on the faces ofthe convolutions 5 to strongly resist displacement. If the helix 3 isalso made of flat strip material, that helix will also set upconsiderable resistance to displacement.

While I have herein stated that the anchorage shall employ two parallelrods between which the two helices are secured by being welded thereto,it will be appreciated that the number of rods between which the helicesare attached may be increased according to the needs of the particularinstallation.

When the anchorage is placed in position and the concrete poured aroundit, the bolt-receiving end 3 is located adjacent one face of theconcrete so that the bolt or other threaded element may enter to engagewith the helix 3.-

Having described one embodiment of the invention, it is obvious that thesame is not to be restricted thereto, but is broad enough to cover allstructures coming within the scope of the annexed claims.

What I claim is:

1. A concrete anchorage comprising a plurality of spaced parallel rods,a spiral helix formed of llat strip metal secured at its peripherybetween the rods, said spiral having its convolutions spaced apart topermit of the entry of concrete between them and to engage the flatsurfaces of the convolutions, said convolutions being of a pitch toengage with the threads of a bolt inserted within the helix, a secondspiral helix secured at its periphery between the rods, the second helixbeing also composed of flat strip metal and having its convolutionsspaced apart for distances greater than the distances between theconvolutions in the first helix, which spacing is such as to preventengagement with the threads of the bolt, the second helix being free ofthe bolt and hav- .ing a free and unencumbered axial passage and beingV, 3 adapted for emhedment in a concrete mass at a greater distance fromthe face of the mass than the bolt-receiving helix, the axial opening inthe second helix permitting the concrete to enter as well as enteringbetween the convolutions of the said helix.

2. A concrete anchorage as provided for in claim 1, wherein the rods areformed with a bend to thereby dispose the axis of the bolt-free helix atan angle to the axis of the bolt-receiving helix, which angle is lessthan a rightvangle. V

References Cited in the file of this patent UNITED STATES PATENTS McOannJuly 30, 1907 Mum-fond Apr. 27, 1915 Mumford June 15, 1915 Richmond June19, 1917 Schenk Nov. 30, 1937 Colt Apr. 19, 1938 Fearon et a1. Apr. 18,1950

